Process got stuck after receiving SIGUSR1

Question

Hi,
I have a C++ program which get stuck after receiving SIGUSR1 signal. Its a daemon process which stop after receiving SIGUSR1 signal. but instead of stopping it stuck.
below is the pstack of the process when it was stuck.
----------------- lwp# 1 / thread# 1 --------------------
7fa1f48c lwp_sema_wait (7e340)
7fa996dc _park    (7e340, 7fabc000, 0, 7e278, 2316c, 0) + 114
7fa993a4 _swtch   (7e278, 7e278, 7fabc000, 5, 1000, 7fabc000) + 424
7fa9ada0 mutexadaptive_lock (7fac785c, 4c00, 1000, fffeffff, 1, 4d58) + 160
7fa9aab4 cmutexlock (7e188, 7fabc000, 0, 33d8c, 0, 0) + 84
00033d8c __1cDstdNbasic_ostream4Ccn0ALchar_traits4Cc___Gsentry2t5B6Mr1_v_ (ffbe9254, 7ce30, 7d278, 7c24c, 8, 7e180) + 50
00031768 __1cDstd2l6Frn0ANbasic_ostream4Ccn0ALchar_traits4Cc____pkc_2_ (7ce30, 66f4d, 7c24c, 0, 0, 0) + 20
00023844 __1cSReplicatorDriver64Jterminate6Fi_v_ (10, 0, 0, 0, 0, 0) + 1c
00023674 __1cSReplicatorDriver64ScatchSignalHandler6Fi_v_ (10, ffbe97f0, ffbe9538, 0, 0, 0) + 1c
7faab118 __sighndlr (10, ffbe97f0, ffbe9538, 23658, 7e320, 7e310) + c
7faa811c sigacthandler (10, 7e278, 0, 0, 0, 7fabc000) + 708
--- called from signal handler with signal 16 (SIGUSR1) ---
7fa1fa6c _write   (7e180, 7e940, ffffffff, 280, 2, 7e000) + c
0005a6a0 __1cDstdNbasic_filebuf4Ccn0ALchar_traits4Cc___Esync6M_i_ (7e180, 8, 7d278, 8, 218, 7ce30) + 30
00031d30 __1cDstd2l6Frn0ANbasic_ostream4Ccn0ALchar_traits4Cc____pkc_2_ (7ce30, 300, 7c24c, 2fd10, 0, 1) + 5e8
0002a548 __1cXTimesTenTableReplicatorEread6MrknXTimesTenLogConnection64_ripppnRttXlaUpdateDesc_t__b_ (803f0, 80430, ffbeaa30
, ffbeaa2c, 2fd10, 8) + 68
00029f98 __1cXTimesTenTableReplicatorJreplicate6Mrl_b_ (803f0, ffbeaaf0, 3e8, 5, 7fb4b4e8, 34) + 108
00028408 __1cYReplicatorThreadDriver64Drun6M_b_ (0, 3fc7c, 8, 7d278, 7ce38, 7e180) + c8
000232c4 __1cSReplicatorDriver64Drun6M_b_ (ffbeabd8, 23258, 7c24c, 2fd10, 0, 1) + 14
00023174 main (3, ffbeac44, ffbeac54, 7c800, 0, 0) + 124
00023028 _start   (0, 0, 0, 0, 0, 0) + 108
below is the code of signal handler.
void ReplicatorDriver64::catchSignalHandler(int i_signalNumber)
     if (i_signalNumber == SIGUSR1 )
     ReplicatorDriver64::terminate(i_signalNumber);
     cout<<"return from ReplicatorDriver64::terminate"<<endl;
     return;
void ReplicatorDriver64::terminate(int i_signalNumber)
     cout << "Received a User Signal 1( terminate ) "<<endl;
     struct sigaction act, oact;
     sigfillset(&act.sa_mask); // set all the signal flags in the sigmask argument
     act.sa_handler = SIG_DFL; // set defaul action flag to segnal
     act.sa_flags = 0;
     m_processStatus = false;
}

Answer 1

The C and C++ standards say that the only thing you can rely on doing in a signal handler is to read and write global volatile variables, abort the program, or call the signal function.
The Unix standard, which applies to Solaris, is more lenient. By default, a signal handler is run on the process stack, although it is possible to specify that a given signal runs on a different stack. If the stack actually used has enough space, you can call functions.
But the Unix standard limits the system functions that you can call. You can call only those system functions that the man page says they reentrant and safe to call from a signal handler. Any function that calls malloc or free is generally not safe, and I/O routines often involve calls to malloc or free.